It was on Wednesday last week that a seriously injured man was found in an apartment in Åtvidaberg.
His life could not be saved.
A 24-year-old man has already been arrested on suspicion of murder.
Initially, a man in his 60s was arrested, but he was released after the criminal suspicions weakened.
Two more suspects
On Monday, two more people were requested to be detained on suspicion of murder.
They are suspected for probable cause, the higher the degree of suspicion.
It's about a man and a woman - both in their upper 20s.
The man is written in Stockholm and the woman must be a resident of Östergötland.
None of them have committed any serious crime before.
The arrest negotiations will take place during the day in Linköping.